Title

Author

Graduation Date

Spring 5-5-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Programs

Medical Sciences Interdepartmental Area

First Advisor

Miao He

Abstract

Transplantation of dopaminergic precursors (DPs) is a promising therapeutic strategy of Parkinson’s disease (PD). However, limited cell source for dopaminergic precursors has become a major obstacle for transplantation therapy. In the first part of the study, we demonstrated that Foxa2 is superior to Lmx1a in inducing dopaminergic neuronal differentiation from induced neural progenitor cells (iNPCs). Based on the results above and some other published results, our group demonstrated that mouse fibroblasts can be reprogrammed into induced dopaminergic precursors (iDPs) through ectopic expression of transcription factors Brn2, Sox2 and Foxa2(1). In the current study, we hypothesized that similar strategy can be applied to generate human iDPs for future cell therapy of PD. We overexpressed transcription factors Brn2, Sox2 and Foxa2 in human fibroblasts and observed formation of neurospheres in the cultures. Subsequent characterization of the precursor colonies confirmed the generation of human induced dopaminergic precursors (hiDPs). These hiDPs were capable of self-renewal, proliferate, and differentiation. The hiDPs demonstrated high co-positive rate of midbrain neural progenitor markers DCX, Corin and neural progenitor marker Nestin by immunostaining. More importantly, the hiDPs also expressed high levels of ventral mesencephalon related neural progenitor marker genes such as Lmx1a, NIKX6.1, Corin, Otx2 and Mash1. After differentiation, those cells exhibited significantly higher levels of major functionally relevant proteins in dopaminergic neurons, including TH, DAT, AADC, Lmx1B and VMAT2. Together, these results suggest that human iDPs can be generated by direct reprogramming of fibroblasts. These human iDPs may serve as a safe and effective cell source for transplantation treatment of PD.